摘要
A comparative study of microsporogenesis in male-sterile and male-fertile grain amaranth was conducted using electron-microscopy.The onset of microsporogenesis breakdown in male-sterile is at the mononuclear pollen stage following the release of microspores from tetrads.Abnormality in the behavior of degenerated tapetum was observed, which failed to envelope individual microspores after their release, leading to an abnormal vacuolation in the mononuclear pollen grains.As a result, the normal thickening of pollen wall could not occur and pollen grains could not engorge, causing male sterility.
栽培种籽粒苋（ＡｍａｒａｎｔｈｕｓｈｙｐｏｃｈｏｎｄｒｉａｃｕｓＬ。）是一种很有潜力的新型作物。它营养价值高、蛋白质含量丰富、氨基酸平衡好、耐旱、耐盐碱和酸、抗逆性强、适应性广，被认为是极有潜力的、为全球提供粮食的替代作物之一。但是籽粒苋千粒重仅０．７～１．２ｇ，种子易散落、植株易倒伏。而且，籽粒苋花冠微小、花期无限，难于采用人工去雄授粉进行杂交育种。于是，和许多其它植物一样，籽粒苋中也找到了雄性不育株。但是它的小孢子发育过程及其败育时期和不育特征尚不清楚，为它的杂交育种研究带来不便。本文通过电镜对雄性可育和不育的两种籽粒苋小孢子分别进行了观察。发现不育小孢子败育起始于四分体释放以后的单核花粉期。在此之前小孢子的发育是一样的。花粉分化早期，孢原组织分化出初级造孢组织、绒毡层、中间层、药壁内层和表皮层（图１）；造孢组织继续分裂，细胞不断扩大，形成小孢子母细胞（图２）；小孢子母细胞不断增大，周围积累胼胝质并逐渐与绒毡层分离，出现大液泡（图３），小孢子母细胞减数分裂，四分体形成，包埋于胼胝质中；绒毡层有丝分裂，有双核细胞；大液泡消失；细胞壁开始降解（图４）。胼胝质逐渐消失，小孢子从四分体中释放以后（单核花粉期），?
